Denial of Reward in the Neonate Shapes Sociability and Serotonergic Activity in the Adult RatReport as inadecuate

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Manipulations of the early environment are linked to long-lasting alterations of emotionality and social capabilities. Denial of rewarding mother-pup interactions in early life of rats could serve as model for child neglect. Negative consequences for social competence in later life, accompanied by changes in the serotonergic system would be expected. In contrast, rewarding mother-pup contact should promote adequate social abilities.

Methodology-Principal Findings

Male Wistar rats trained in a T-maze during postnatal days 10–13 under denial DER or permission RER of maternal contact were tested for play behavior in adolescence and for coping with defeat in adulthood. We estimated serotonin 5-HT levels in the brain under basal conditions and following defeat, as well as serotonin receptor 1A 5-HT1A and serotonin transporter SERT expression. DER rats exhibited increased aggressive-like play behavior in adolescence i.e. increased nape attacks, p<0.0001 and selected a proactive coping style during defeat in adulthood higher sum of proactive behaviors: number of attacks, flights, rearings and defensive upright posture; p = 0.011, p<0.05 vs RER, non-handled-NH. In adulthood, they had lower 5-HT levels in both the prefrontal cortex p<0.05 vs RER and the amygdala p<0.05 vs NH, increased 5-HT levels following defeat PFC p<0.0001 and decreased serotonin turnover amygdala p = 0.008. The number of 5-HT1A immunopositive cells in the CA1 hippocampal area was increased p<0.05 DER, vs RER, NH; SERT levels in the amygdala were elevated p<0.05 vs RER, NH, but were lower in the prefrontal cortex p<0.05 vs NH.


Denial of expected maternal reward early in life negatively affects sociability and the serotonergic system in a complex manner. We propose that our animal model could contribute to the identification of the neurobiological correlates of early neglect effects on social behavior and coping with challenges, but also in parallel with the effects of a rewarding early-life environment.

Author: Anastasia Diamantopoulou, Androniki Raftogianni, Antonios Stamatakis, Filaretos Alikaridis, Melly S. Oitzl, Fotini Stylianopoulou



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